The present invention relates generally to composites and, more particularly, to polymer composites containing inorganic or organic materials disposed in the polymer matrix""s free volume and to oxyhalopolymer composites and surface-oxyhalogenated non-halopolymer composites, and to methods of making and using same.
Inorganic-organic hybrid materials have been used with varying degrees of success for a variety of applications.
In some of these materials, organic polymers are blended with inorganic fillers to improve certain properties of those polymers or to reduce the cost of the polymeric compositions by substituting cheaper inorganic materials for more expensive organic materials. Typically, inorganic fillers are either particulate or fibrous and are derived from inexpensive materials, such as naturally occurring minerals and glass. For example, U.S. Pat. No. 5,536,583 to Roberts et al. (xe2x80x9cRobertsxe2x80x9d) describes methods for mixing inorganic ceramic powders into polyethersulfones, polyether ketones, and polyether ether ketones and methods for including metal nitrides, oxides, and carbides into fluoropolymer resins to produce corrosion inhibiting coatings as well as coatings which have improved abrasion resistance and/or enhanced bonding characteristics. U.S. Pat. No. 5,492,769 to Pryor et al. (xe2x80x9cPryorxe2x80x9d) describes methods for embedding metal or ceramic materials into organic polymeric materials to increase the polymer""s abrasion resistance. U.S. Pat. No. 5,478,878 to Nagaoka et al. (xe2x80x9cNagaokaxe2x80x9d) describes a thermoplastic blend of an organic polymer and inorganic metallic fillers which improves the polymer""s resistance to discoloration upon exposure to ambient light sources.
Each of the above inorganic-organic hybrid materials were made either (1) by melting and then mixing the inorganic and organic phases into a homogeneous mixture which was then cured, extracted, or dried or (2) by dissolving the polymer and inorganic material together in a solvent in which both materials were miscible, mixing to produce a homogeneous solution, and then evaporating the solvent to extract the hybrid material. The resulting inorganic-organic hybrid materials are essentially homogeneous macromolecular blends which have separate inorganic and organic domains which range from nanometers to tens of micrometers in size. All of the above composites are fabricated by using inorganic materials, typically naturally occurring minerals, which are in thermodynamically stable metallic forms, such as metal oxides, metal nitrides, and zero-valent metals.
These inorganic-organic hybrid materials suffer from a number of drawbacks which limit their utility. For example, the size of the domain that the inorganic materials assume within the hybrid depends on the particle size of the inorganic material particulate or fiber used in making the hybrid. In addition, the homogeneity of the inorganic-organic hybrid material largely depends on either the solubility of the inorganic material in the polymeric melt or on the solubility of the inorganic material in the solvent used to solubilize the polymeric material. Furthermore, the properties and molecular structures of these hybrids depend greatly on the methods used to extrude, cast, or dry the solid hybrid material from the melt or solubilized mixtures, which gives rise to significant, undesirable, and frequently uncontrollable batch-to-batch and regional variations.
Inorganic-organic hybrid materials have also been prepared by dispersing powdered or particulate forms of inorganic materials within various polymeric matrices.
For example, U.S. Pat. No. 5,500,759 to Coleman (xe2x80x9cColemanxe2x80x9d) discloses electrochromic materials made by dispersing electrically conductive metal particles into polymeric matrices; U.S. Pat. No. 5,468,498 to Morrison et al. (xe2x80x9cMorrisonxe2x80x9d) describes aqueous-based mixtures of colloidal vanadium oxide and dispersed sulfonated polymer which are useful for producing antistatic polymeric coatings; U.S. Pat. No. 5,334,292 to Rajeshwar et al. (xe2x80x9cRajeshwarxe2x80x9d) discloses conducting polymer films containing nanodispersed inorganic catalyst particles; and U.S. Pat. No. 5,548,125 to Sandbank (xe2x80x9cSandbankxe2x80x9d) discloses methods for melt- or thermo-forming flexible polymeric gloves containing particulate tungsten which makes the gloves useful for shielding x-radiation.
Although the inorganic-organic hybrid materials are homogeneously mixed, they contain separate inorganic and organic phases on a macromolecular scale. These separate phases frequently gives rise to the inorganic material""s migration within and/or leaching out of the polymeric matrix. Furthermore, the inorganic phases of these inorganic-organic hybrid materials can be separated from the polymer matrix by simple mechanical processes or by solvent extraction of the polymer. Consequently, upon exposure to certain temperatures or solvents, the inorganic phases of these hybrids can migrate and dissipate out of or accumulate in various regions within the polymeric matrix, reducing its useful life.
Because of the problems associated with migration and leaching of the inorganic phase in inorganic-organic hybrids, hybrid materials containing inorganic phases having greater stability have been developed. These materials rely on physically entrapping large interpenetrating macromolecular networks of inorganic materials in the polymeric chains of the organic material.
For example, U.S. Pat. No. 5,412,016 to Sharp (xe2x80x9cSharpxe2x80x9d) describes polymeric inorganic-organic interpenetrating network compositions made by mixing a hydrolyzable precursor of an inorganic gel of Si, Ti, or Zr with an organic polymer and an organic carboxylic acid to form a homogeneous solution. The solution is then hydrolyzed, and the resulting hybrid materials are used to impart added toughness to conventional organic polymers as well as to increase their thermal stabilities and abrasion resistances. U.S. Pat. No. 5,380,584 to Anderson et al. (xe2x80x9cAnderson Ixe2x80x9d) describes an electrostatography imaging element which contains an electrically-conductive layer made of a colloidal gel of vanadium pentoxide dispersed in a polymeric binder. U.S. Pat. No. 5,190,698 to Coltrain et al. (xe2x80x9cColtrain Ixe2x80x9d) describes methods for making polymer/inorganic oxide composites by combining a polymer derived from a vinyl carboxylic acid with a metal oxide in a solvent solution, casting or coating the resulting solution, and curing the resulting sample to form a composite of the polymer and the metal oxide. These composites are said to be useful for forming clear coatings or films having high optical density, abrasion resistance, or antistatic properties. U.S. Pat. No. 5,115,023 to Basil et al. (xe2x80x9cBasilxe2x80x9d) describes siloxane-organic hybrid polymers which are made by hydrolytic condensation polymerization of organoalkyoxysilanes in the presence of organic film-forming polymers. The method is similar to that described in Sharp and, similarly, is used to improve a polymer""s mechanical strength and stability while maintaining its flexibility and film forming properties. U.S. Pat. No. 5,010,128 to Coltrain et al. (xe2x80x9cColtrain IIxe2x80x9d) describes methods for blending metal oxides with etheric polyphosphazenes to increase abrasion resistance and antistatic properties of polyphosphazene films. These methods, like those of Coltrain I, employ inorganic metal precursors which contain hydrolyzable leaving groups.
In each of the foregoing, the polymeric inorganic-organic interpenetrating network compositions are obtained by, sequentially, (1) adding hydrolyzable metals (or hydrolyzed metal gels) into either a polymer melt or a solvent containing a dissolved polymer; (2) adding a hydrolyzing agent or adjusting the pH of the solution to effect hydrolysis; (3) mixing; and (4) curing.
The methods described, however, suffer from several limitations. For example, they are limited to incorporating interpenetrating metal oxide networks into polymers which have similar solubilities as the hydrolyzable metal precursors or the hydrolyzed metal. In addition, because the method involves first mixing the inorganic hydrolyzable metal precursors or the hydrolyzed metal with the organic polymer and then curing the mixture, curing of the inorganic phase and organic phase necessarily occurs simultaneously. Since both the inorganic and organic materials are in intimate contact during the curing process, the organic phase of the resulting hybrid has physical characteristics different from that of the same polymer cured in the absence of an inorganic phase. This makes it difficult and, in many cases, impossible to predict the concentration of inorganic material necessary to preserve the desired properties of the starting organic polymer material or to predict the properties of the resulting hybrid. Typically, crystallinity and/or free volume in the hybrid materials are significantly different than the starting organic polymer materials cured in the absence of the inorganic phase. The methods also have limited utility because they provide no control over the spatial distribution of the inorganic and organic phases within the polymeric inorganic-organic interpenetrating network hybrid. For example, it is difficult and, in many cases, impossible to control which phase dominates the surface of the bulk material or the surface of the free volume within the bulk material. This variability can cause quality control problems as well as limit the usefulness of the hybrid materials with respect to bulk versus surface properties.
Alternatively, it has been demonstrated that inorganic and organic molecules can be impregnated into solid matrices using supercritical fluids.
WO 94/18264 to Perman et al. describes the use of supercritical fluids for impregnating a variety of specific additives into polymer substrates by simultaneously contacting the polymer substrate with the impregnation additive and a carrier liquid, such as water, in the presence of a supercritical fluid. The described method requires that a polymeric material be simultaneously exposed to an impregnation additive and a carrier liquid, and, then, all three of these components are exposed to a supercritical fluid in a high pressure vessel for a sufficient time to swell the polymeric material so that the carrier liquid and impregnation additive can penetrate the swollen polymeric material.
In Clarke et al., J. Am. Chem. Soc., 116:8621 (1994), supercritical fluid is used to impregnate polyethylene with CpMn(CO)3 using supercritical CO2 which acts to both solvate the CpMn(CO)3 and to swell the polyethylene, thus permitting the flow of CpMn(CO)3 into the free space created in the swollen polymer and into the free volume of the polymeric material.
Watkins et al., Macromolecules, 28:4067 (1995) discloses methods for polymerizing styrene in supercritical CO2-swollen poly(chlorotrifluoroethylene) (xe2x80x9cPCTFExe2x80x9d).
Methods for impregnating polymeric materials with additives using supercritical fluids suffer from a number of important drawbacks. First, the method requires the use of a high pressure apparatus. Second, the method requires that the supercritical fluid or another suitable carrier solvent be available to solvate the additive to be impregnated in the polymer matrix. Third, the method requires that the polymeric material be grossly swollen to permit the additive to penetrate and, thus, to impregnate the polymeric material. This swelling results in large changes in the host polymer""s surface and bulk morphology and also results in a lack of control of the final hybrid material""s composition. Finally, this method allows no control over the resulting surface properties of the hybrid materials. Together, these changes and lack of control lead to a variety of physical and chemical changes in the host polymer, including changes in properties such as flexibility, crystallinity, and thermal characteristics. Finally, in most cases where supercritical methods are used to impregnate additives into polymeric materials, the impregnated additive can be readily diffused out of the polymeric material by exposure of the polymeric material to supercritical fluid conditions or, in some cases, to various solvents.
For these and other reasons, there remains a need for inorganic-organic polymer composites and for methods of preparing these inorganic-organic polymer composites which do not suffer from the above-described limitations as well as for methods of preparing these composites which permit control over the surface peroperties (e.g., wetability, reactivity, adhesiveness, and physical and chemical toughness). The present invention is directed to meeting this need.
Man-made structures, such as boat hulls, buoys, drilling platforms, oil production rigs, bridges, piers, locks, and pipes which are immersed in or in intermittent contact with water are prone to fouling by aquatic and marine organisms, such as green and brown algae, barnacles, mussels, and the like. Such structures are commonly made of metal, but may also include other materials, such as concrete, wood, and plastic. On boat hulls, fouling increases the frictional resistance towards movement through the water, with the consequence of reduced speeds and increased fuel costs. On static structures, such as the legs of drilling platforms, oil production rigs, bridges, and piers, the resistance of thick layers of fouling to waves and currents can cause unpredictable and potentially dangerous stresses in the structure. Moreover, fouling also makes it difficult to inspect the structure for defects, such as stress cracking and corrosion. In pipes, such as cooling water intakes and outlets, fouling reduces the pipe""s effective cross-sectional area, which results in reduced flow rates.
The commercially most successful method of inhibiting fouling have involved the use of anti-fouling coatings which release substances toxic to aquatic or marine life, for example tributyltin chloride or cuprous oxide. Such coatings, however, are being regarded with increasing disfavor because of the damaging effects these toxins can have on the aquatic or marine environment into which they are released. There is, accordingly, a need for anti-fouling coatings which do not release toxic materials.
The present invention relates to a composite. The composite includes a polymer matrix having a natural free volume therein and an inorganic or organic material disposed in the natural free volume of the polymer matrix.
The present invention also relates to a method for making a composite. A polymer matrix having free volume therein is provided. The free volume of the polymer matrix is evacuated, and inorganic or organic molecules are infused into the evacuated free volume of the polymer matrix. In a particularly preferred embodiment of the present invention, the inorganic or organic molecules are then polymerized under conditions effective to assemble the inorganic or organic molecules into macromolecular networks.
The present invention also relates to a composite which includes a polymer matrix having natural free volume therein. The composite also includes an inorganic or organic material disposed in the natural free volume of the polymer matrix. The polymer matrix is at least partially amorphous and includes a functionality, and the inorganic or organic material interacts with said polymer matrix""s functionality.
The present invention further relates to a method for making a composite. The method includes providing a polymer matrix having free volume therein, where the polymer matrix is at least partially amorphous and includes a functionality. The free volume of the polymer matrix is evacuated, and inorganic or organic molecules are infused into the evacuated free volume of the polymer matrix. The method further includes treating the inorganic or organic molecules under conditions effective to cause the inorganic or organic molecules to interact with the polymer matrix""s functionality. The present invention also relates to another method for making a composite. In this method, an at least partially amorphous polymer matrix having free volume and a catalyst disposed therein is provided. The free volume of the polymer matrix is evacuated, and inorganic or organic molecules are infused into the evacuated free volume. The method further includes polymerizing the inorganic or organic molecules under conditions effective to assemble the inorganic or organic molecules into macromolecular networks, where the catalyst promotes said polymerizing.
The present invention also relates to a method for oxidizing an oxidizable substrate. The method includes contacting the oxidizable substrate with an oxidizing agent in the presence of a composite. The composite includes a polymer matrix having natural free volume therein and an inorganic or organic material disposed in the natural free volume of the polymer matrix.
The present invention also relates to a method for preventing fouling of a surface by organisms. The method includes applying, to the surface, a composite that includes a polymer matrix having free volume therein and an inorganic or organic material disposed in the polymer matrix""s free volume.
The present invention also relates to another method for preventing fouling of a polymer surface by organisms. The polymer surface includes a polymer matrix having free volume therein. The polymer matrix""s free volume is evacuated, and inorganic or organic molecules are infused into the evacuated free volumes.
The present invention also relates to an object. The object has a surface, all or a portion of which comprises a polymer matrix having free volume therein and an inorganic or organic material disposed in the free volume of the polymer matrix.
The present invention also relates to a method for making an oxyhalopolymer composite. The method includes providing an oxyhalopolymer which has free volume therein. The oxyhalopolymer""s free volume is evacuated, and inorganic or organic molecules are infused into the evacuated free volume of the oxyhalopolymer.
The present invention also relates to another method for making an oxyhalopolymer composite. In this method, a halopolymer composite is provided. The halopolymer composite""s surface halogen atoms are then modified under conditions effective to substitute at least a portion of the halopolymer composite""s surface halogen atoms with hydrogen atoms and oxygen atoms or oxygen-containing radicals.
The present invention also relates to a method for making a surface-oxyhalogenated non-halopolymer composite. The method includes providing a surface-oxyhalogenated non-halopolymer having free volume therein. The method further includes evacuating the free volume of the surface-oxyhalogenated non-halopolymer, and infusing inorganic or organic molecules into the evacuated free volume of the surface-oxyhalogenated non-halopolymer.
The present invention also relates to another method for making a surface-oxyhalogenated non-halopolymer composite. In this method, a surface-halogenated non-halopolymer composite is provided. The method further includes modifying the surface-halogenated non-halopolymer composite""s surface halogen atoms under conditions effective to substitute at least a portion of the surface-halogenated non-halopolymer composite""s surface halogen atoms with hydrogen atoms and oxygen atoms or oxygen-containing radicals.
The present invention, in another aspect thereof, is related to an oxyhalopolymer composite. The oxyhalopolymer composite includes an oxyhalopolymer having free volume therein and an inorganic or organic material disposed in the free volume of the oxyhalopolymer.
The present invention also relates to a surface-oxyhalogenated non-halopolymer composite. The composite includes a surface-oxyhalogenated non-halopolymer having free volume therein and an inorganic or organic material disposed in the free volume of the surface-oxyhalogenated non-halopolymer.
The composites of the present invention contain polymeric phases which have physical properties substantially similar to the properties of the native polymer matrix (i.e., polymer matrix in the absence of inorganic or organic molecules or macromolecular networks). Consequently, the composites of the present invention, relative to conventional inorganic-organic hybrid materials, have significantly more predictable mechanical properties. The composites of the present invention also have controllable, predictable, and reproducible levels of optical densities and electrical, ionic, and charged species conductivities, which make them useful in various applications including photoradiation shields and filters, electromagnetic radiation shields and filters, heterogeneous catalytic substrates, and conducting electrodes. These characteristics also make these composites useful as components in the construction of electrolytic cells, fuel cells, optoelectronic devices, semiconductors for microelectronic applications, and materials having flame and heat retardant properties.
Although the initial formation of these composites results in materials having physical properties substantially similar to those of the native polymeric matrix, subsequent thermal, chemical, photochemical, or electrochemical treatment of the composites produced in accordance with the present invention can lead to improved physical properties. It is believed that these changes in the physical properties of the composite result from chemical and/or electronic interactions between the infused inorganic or organic molecules and the polymer matrix.
In addition, composites of the present invention can have a surface which optionally contains halogen atoms, a portion of which have been replaced with hydrogen atoms and oxygen atoms or oxygen-containing groups. The oxyhalopolymer surface retains many of the positive attributes characteristic of halopolymer surfaces, such as tendency to repel water and other polar solvents, high thermal stability, and low adhesion and friction coefficients. However, unlike halopolymer surfaces, the surfaces of the oxyhalopolymer composites of the present invention have reactive chemical sites which permit bonding with other chemical functionalities, such as organosilicons, organometallic precursors, transition metal ions and compounds, transition metal films, fluorescent compounds and other dyes, and biological materials, such as proteins, enzymes, and nucleic acids. In addition, by proper choice of the infused inorganic material and chemical functionality at the surface, polymer composites having an inorganic surface which is the same as, silmilar to, or different from the infused inorganic material can be prepared. Such materials are useful, for example, in preparing metal oxide/fluoropolymer composites having a pure metal oxide surface.